Apparatus for providing failure planes in concrete



0, 1966 R. BEESLEY ETAL 3,269,282

APPARATUS FOR PROVIDING FAILURE PLANES IN CONCRETE Filed Jun 11, 1964 2Sheets-Sheet 1 IN VEN TORS Rodi/97' 4 55:54 E) Aug. 30, 1966 R. L.BEESLEY ETAL 3,269,282

APPARATUS FOR PROVIDING FAILURE PLANES IN CONCRETE Filed June 11, 1964 2Sheets-Sheet 2 INVENTORS /?0fi'/?7' 4. 5555.45) FIG- 5 ROBERT/T 49/41Unite States Patent O Calif.

Filed June 11, 1964, Ser. No. 374,495 7 Claims. (Cl. 94-39) Thisinvention relates to a method and apparatus for the placing of failureplanes in concrete during the finishing of the concrete, and inparticular relates to an improved method and apparatus for placing suchfailure planes during concrete road construction.

conventionally, large expanses of concrete such as concrete roadways areprovided with weakened planes to provide failure planes for cracking ofthe concrete, thereby avoiding random breaking. In one method theconcrete is finished and, after it has hardened, the surface is cut witha diamond saw. This method is quite expensive since it requires the useof elaborate machinery and extensive time. In a second technique, apartitioning strip can be embedded in the concrete While it is stillplastic. Stresses produced in the concrete after it has hardened causeit to crack along the partitioning strip leaving a failure line on thesurface. While this technique is usually less costly and time consumingthan sawing, heretofore, no machines or techniques have been designedthat satisfactorily bury the partitioning strip in the concrete. Acommon difficulty with flexible strip burying machines is that theyapply an uneven tension on the flexible strip as it is embedded in theconcrete which causes the edge of the strip under lesser tension to foldin a random fashion. The concrete frequently spalls about the folds ofthe flexible strip and provides an uneven failure joint with pittededges.

It is an object of this invention to provide a method and machine toplace failure planes in concrete which will cause clean separationbreaks in the concrete upon stress.

It is also an object of this invention to incorporate such means withmechanical screeding machines employed for construction of concreteroadways.

It is a further object of this invention to provide an improved methodfor embedding a separation membrane within a plastic mass such as aconcrete bed.

Other and related objects will be apparent from the followingdiscussion.

We have now found that the aforementioned spallin g and pittingcharacteristics of concrete failure planes, achieved by prior arttechniques, can be avoided by careful placement of a ribbon ofseparation membrane in the concrete. Hereinafter, the specificallydescribed separation strip material is a plastic ribbon, but it isapparent that any flexible ribbon or the equivalent can be used in lieuthereof in the practice of my invention such as a metal foil strip, apaper strip, an asphalt impregnated paper strip or, preferably, any of avariety of plastic strips. Specifically then, one embodiment of ourinvention comprises introducing a plastic strip into :a concrete surfaceat a particular angle of incidence thereto and at a controlled, desiredplacement depth by folding the plastic strip along a desired failureplane with a fold having an angle of inclination to said failure planewhich is about half the said angle of incidence of said plastic strip tosaid concrete surface. In this manner, since no uneven tension isapplied across the plastic strip, the strip is laid into the concretesurface free from folds, crimps, or undesired zigzags. In its preferredembodiment, the plastic strip edge is introduced into the concrete atright angles to the surface thereof, being folded along a fold at 45degrees to said surface so as to embed the plastic strip on its edgealong a plane parallel to said concrete surface.

ICC

A novel plastic strip applicator which can be employed in our inventionfor placement of the plastic strip within a concrete mass comprises, ingeneral, a blade, means to immerse said blade into the plastic concretemass, means to move said immersed blade through said concrete, plasticstrip folding means integral with said blade, and means to feed aplastic strip to said folding means. Our invention can also comprise avibratory means integral with said strip applicator to facilitateintroduction of the plastic strip and to compact or smooth the surfaceafter passage of said application means.

Our invention will now be described by reference to the drawings ofwhich:

FIGURE 1 depicts the path of a plastic strip and the direction of foldemployed in my invention;

FIGURE 2 illustrates a preferred embodiment of my invention, the bladehaving folding means incorporated therein;

FIGURE 3 illustrates the plastic strip embedding means of my invention;

FIGURE 4 is a plan view of a ribbon placement machine useful infinishing concrete roadways;

FIGURE 5 illustrates the assembly of a strip applicator means of ourinvention including a ribbon placement machine as depicted in FIGURE 4.

FIGURE 5 illustrates a modification of the assembly of FIGURE 2 whereina shield is incorporated to protect the flexible strip; and

FIGURE 7 is a plan view of the FIGURE 6 apparatus.

Referring now to FIGURE 1, there is shown a cross section of concretemass 1 in which plastic strip 2 is to be embedded along an edgewiseplane parallel to top surface 8 of concrete mass 1. Plastic strip 2 isapplied from roll 3 and directed into concrete surface 8 along an angleof incidence thereto, shown as A. To avoid uneven tension in plasticstrip 2, it is apparent that the distance bc along the top edge ofplastic strip 2 must equal distance ad. The fold a-c thus comprises acommon hypotenuse for the respective right triangles abs and adc.Accordingly, for the legs of these triangles, ad and b-c to be the samelength, it is necessary that acute angles B and B be equal. Since angleA equals the sum of angles B and B it therefore is apparent that theangle of the fold relative to the edge of plastic strip 2 in theconcrete, angle B must be half the angle of incidence, angle A, ofplastic strip 2 relative to concrete surface 8. Hence, the improvedmethod of our invention comprises the introduction of a plastic stripedge into a concrete surface at an angle incident to the surface thereofand, at the desired depth of placement of said plastic strip, foldingsaid plastic strip into .an edgewise plane parallel to said concretesurface along a fold having an angle which is half said angle ofincidence.

Referring now to FIGURE 2, there is illustrated the preferred angles ofincidence and fold of our invention together with blade means forintroducing the plastic strip into a wet concrete mass and folding meansintegral with said blade to fold said plastic strip along an edgewiseplane at the desired depth of penetration. In this ill-ustration,plastic strip 2 is supplied at a right angle to surface 8 of concretemass 1 and passed through slot or eye 5 of blade 6, eye 5 beingsupported at a 45 degree angle to top surface 8 of concrete mass 1. Thedepth to which blade 6 is inserted into plastic concrete mass 1regulates the placement of plastic strip 2 beneath concrete surface '8.Typically, placement depths for the top edge of the strip from aboutone-eighth inch above to about one eighth inch below concrete topsurface 8 are employed. Preferably, the top edge of the strip is flushwith concrete top. surface 8. However, placement depths of severalinches below concrete top surface 8 can be used for specialapplications.

When using deep ribbon placements, a shield or deflector 4 is used asillustrated in FIGURES 6 and 7. Deflector 4, as shown in FIGURE 6,prevents aggregate, and the concrete mix generally, from catching strip2 as it passes along the surface of blade 6 prior to entering slot 5.Preferably, the edges of slot 5 are rounded or smoothed to avoid tearingof plastic strip 2. it is also preferred to bevel the forward lowercorner '7 of blade 6 to facilitate movement of blade 6 through wetconcrete mass 1. Eye 5 is preferably located as close as practical tothe forward edge of blade 7 so that when the blade comes to a header, asin a transverse strip placement, the flexible strip will be almostagainst the header. Blade 6 is kept to a minimum thickness for ease ofpass-age through the concrete, the only limitation being sufficientstructural stability for construction use.

Referring now to FIGURE 3, there is illustrated one embodiment of theplastic ribbon embedding assembly of our invention. The assembly isemployed to embed plastic strip 9 beneath a wet or plastic concrete mass10'. The plastic strip 9 is preferably supplied to the assembly on adrum or reel 11. Plastic strip 9* can be of any suitable plasticmaterial, e.g., polyethylene, polyvinylchloride, and the like. The widthof plastic strip 9 usually is from about one to about three inches ormore, preferably about two inches, and usually varies in thickness fromone mil or less to about twenty-five mils or more. However, the stripwidth is not critical and can be as low as three-eighths inch or lowerand as high as six inches or more. Further, the strip thickness is notcritical as long as the strip is flexible and can be as thick asthree-sixteenths of an inch or more. Preferably, when using a plasticstrip, thicknesses from about two to about six mils are employed.

Reel 11 is supported between uprights 12 which can be attached to theframe of the assembly. As previously mentioned, uprights 12 arevertical, i.e., perpendicular to the concrete top surface so that theangle of incidence of plastic strip 9 to the concrete surface is 90degrees and a 45 degree fold is used beneath the concrete surface. Otherangles of incidence can of course be used without departing from thespirit of the invention. To support the assembly on the equipment, twobrackets 14 and 15 are employed. These brackets are joined at one endand spread at their opposite ends to form a triangular support. The baseof the brackets are fastened to a mounting plate 16 which can beattached to a frame or bed member 17 in the bed of a concrete screedingor finishing machine, or any other suitable movable strip placementsupport means. A plastic strip deflecting plate 13 can be positionedbetween the vertical uprights 12 to guide the plastic strip.

Extending downwardly from the lower bracket 15 is concrete cutting blade18 which has plastic strip folding means comprising an eye or groove 19.Preferably, the entire assembly is attached to bed-member 17 by alinkage that permits vertical adjustment of the depth of blade 18 inconcrete mass 10 and permits retraction of blade 18 from concrete mass10 after the strip has been placed. Concrete cutting blade 18 isadjustable vertically by moving mounting plate 16 up and down on boltsinserted from frame 17 through elongated slots 61 and 62 in mountingplate 16. Also attached to blade 18 is a suitable vibrator which isadapted to vibrate blade 18 and facilitate its path through concretemass 10. A vibrator is usually needed for strip placement whenrelatively large aggregate is used in the concrete mix. However, withcertain consistency concrete mixes, a vibrator may not be required. Anysuitable vibrator 20 can be used such as a weight which is driven aroundan eccentric race by air pressure, a motor driven cam arrangement, asolenoid type vibrator, or the like. A generally flat trowelling means(not shown) can be placed above the blade at the concrete top surface totrowel the concrete as the assembly moves across the concrete surface.

To eliminate unnecessary twists in plastic strip 9 it is preferred toposition plastic strip reel 11 as shown, i.e.,

with its axis along the path of motion. It is, of course, apparent thatreel 11 can be positioned in any other angle and suitable means employedto feed plastic strip 9 in the manner illustrated. Also, if desired, asuitable ten sioning means 21 can be employed to hinder the freerotation of reel 11 or dampen its motion to avoid backlashing of strip 9on reel 11. To insure that plastic strip 9 is at the proper angulardisposition to eye 19 in blade 18, strip guides such as 22 can beemployed on member 13. As illustrated, blade 18 is an extension ofelement 13 and accordingly guides 22 can be rigidly affixed to member13. In other embodiments, these guides can be adjustable so that theangle of incidence of plastic strip 9 to the top surface of concretemass 10 can be controlled to insure that strip 9 is fed to eye 19 at theproper angle of incidence so :as to avoid any unbalance in tension onstrip 9.

As described in regard to FIGURE 3, the strip embedding assembly can beattached to the frame member of a concrete screeding machine. An exampleof such a machine is that employed for the mechanical finishing ofconcrete roadways. As illustrated, the strip placement assembly can bebolted to the trailing frame member of such a screeding machine andthereby employed for positioning a continuous plastic strip along thelength of the finished roadway. A typical method of starting the stripin a new roadway is to drive a stake at the beginning and tie the stripend hereto or to clamp the strip end to the beginning header. Once thestrip has been laid a few inches, holding means are not required as theconcrete grips the flexible strip. It is also necessary to providefailure planes which traverse the roadway and the plastic ribbonplacement assembly of our invent-ion can be adapted for this use also.Further, our invention is applicable to any concrete mass of any size ordepth and thus is not limited to use in roadway construction.

FIGURE 4 illustrates a plan view of a ribbon placement machine accordingto our invention which can be used to place plastic strips whichtraverse roadway 60. This machine comprises a generally rectangularlyshaped frame composed of transverse beams 15 and longitudinal beams 16.Beneath each beam is an axle 28 which supports wheels 2-9 at either endthereof. A drive motor 17 is employed to move the assembly forward andguide trowels 1'8 and 21 direct the machine along the road bed. Rightand left holding trowels 19 and 20 are positioned beneath the machineframe to maintain proper forward direction. .The aforementioned trowels18, 19, 20, and 21 are supported on downwardly directed legs which arespringtensioned to transmit a compacting force from each trowel to theconcrete mass. A catwalk 22 and operators plat form 23 can be placed onthe front transverse carriage beam 15 and the-machine controls can bepositioned on platform 23' for control of the machine.

A plastic strip placement assembly, similar to that previouslydescribed, is shown as element 24 riding on transverse carriage or track25 which is supported at opposite ends of the machine. Preferably thistrack 25 is supported from the machine frame by hydraulic cylinders 26which can be used to control the vertical height of track 25 above theconcrete road bed and, hence, control the depth of the plastic stripplacement in the concrete and also eifect removal of plastic stripplacement assembly 24 from the concrete mass after the laying of plasticribbon. A separate drive motor 27 is employed to move the plastic stripassembly 24 on track 25. The angle of track 25 to the main axis of themachine and the road bed longitudinal axis is illustrated at an angle ofabout 7 from the perpendicular to said axis. This angle provides vehiclewheel contact with the failure planes at different times, thus reducingthe thumping characteristic of concrete roadway travel. The particularshape and construction of the plastic strip assembly 24, track 25, andpower supply 27 can be similar to that hereafter described regard toFIGURE 5.

FIGURE 5 illustrates a portable plastic strip placement machine that canbe manually positioned on concrete road bed 52 or on any extendedconcrete surface. This construction employs an I-beam track supported ateither end by A-frames 31 and 32 which have feet 33 adapted forpositioning on the edge of the concrete or on the concrete-retainingforms 53 as shown. A handle 34 is also placed at each end of theassembly. Preferably, the apex of the A-frame comprises support 35through which the track 30 extends. To permit the position of A-frames31 and 32 to be varied according to the Width of the concrete or roadbed, pins 36 are employed to lock into any of a series of holes boredinto the upper flange of I-beam track 30. The plastic strip placementassembly is supported on I-bearn track 30 by a box 37 which is slidablealong I-beam track 30. Preferably, two or more rollers 38 are providedon each side of the I-bearn web of I-beam track 30 to roll upon theupper surface of the lower flange. In this manner, a rolling contact ofthe assembly on I-beam track 30 is obtained.

Box 37 supports the assembly on a downwardly dependant leg 40. Eyes 41are placed on this leg and threaded with a cable 42 which passes overdrive pulley 43 and idler pulley 44. The drive motor 46 is mounted atone end of the assembly to drive pulley 43 through a suitable clutch 47.Preferably, drive motor 46 is reversible or drives pulley 43 through areversible gear train so that the assembly can be readily returned tothe opposite end of track 30 for the next strip placement. The reel ofplastic strip 48 is supported on vertical uprights 39 in the mannerpreviously described in regard to FIGURE 3. At the base of leg 40 ismounted a suitable finishing shoe 49 having an upwardly turned lip 50 atits leading edge. Beneath shoe 49 is mounted a blade, such as blade 18having a plastic holding eye 19 as previously described in regard toFIGURE 3. A suitable vibrator 51 can be employed on shoe 50 tofacilitate passage of the blade through the wet concrete mass 52.

As previously mentioned, the failure planes are to be positionedlongitudinally and transversely to the concrete roadway. Accordingly, inthe placement of the second set of plastic strips it is necessary totraverse or intersect a previously positioned plastic strip. It ispreferred to employ a blade such as 18, described in FIGURE 3, having asharp leading edge so that this plastic strip will be cut cleanlywithout pulling out of place. It is also within the scope of ourinvention to employ other means for severing the previously placedplastic strip. In one embodiment, an electrical resistance wire can beplaced along the lower beveled edge of plate 18. The opposite ends ofthis resistance Wire can be connected to any suitable electrical supply,e.g., storage battery or electrical generator, by a switch which can bemanually or automatically controlled to close the circuit and heat thiswire when the knife edge approaches or contacts the plastic strip. Thehot wire will melt the plastic strip and thereby produce a clean breakto permit blade 18 to traverse this previously placed strip. It is, ofcourse, apparent that other obvious means such as remotely controlledknife blades or other cutting devices can be employed to severpreviously placed ribbons and thus permit blade 18 to traverse thisribbon.

While the previous discussion has delt with the use of our invention inlaying concrete masses, it is to be understood that our invention isapplicable to use with any material through which a flexible, foldableribbon can be laid. Further, the flexible strip used with materialsother than concrete can comprise any of the aforementioned materialssuch as metal strips, paper strips, plastic strips, wood strips, ortheir equivalents. Also, although the previous discussion has related tothe placement of flexible ribbon widths substantially perpendicular toconcrete surfaces, i.e., on edge, it is to be understood that it iswithin the scope of our invention for the width to be placed at anydesired angle to the concrete top surface which is easily accomplishedby merely tilting the blade transversely to the direction of bladetravel.

It is not intended that our invention be unduly limited or restricted bythe specific illustrations and mode of practice herein set forth. Ratherour invention is intended to be described by the steps or their obviousequivalents of the following method claims, and the elements or theirobvious equivalents of the following apparatus claims.

We claim:

1. A flexible ribbon placement means comprising:

a generally flat blade having two sides;

means to immerse said blade in a plastic mass having a top surface;

means to move said immersed blade through said plastic mass;

an inclined guide carried by said blade, said inclined guide having astraight edge adapted to contact and fold a flexible ribbon as it passesfrom one side of said blade to the other, said means to immerse beingadapted to position said blade with its plane in the direction of itsmotion so that said straight edge extends beneath said top surface at aninclined angle to said top surface; and

means to feed a flexible ribbon along one side of said blade to saidguide, said means to feed being adapted to feed said flexible ribbon sothat the edge of said ribbon is at an angle incident to said topsurface, said incident angle being twice said inclined angle.

2. A flexible ribbon placement means comprising:

a generally flat :blade having two sides;

means to immerse said blade in a plastic mass having a top surface;

means to move said immersed blade through said plastic mass;

a lateral opening through said blade, the top edge of said opening beinga straight edge adapted to contact and fold a flexible ribbon as itpasses through said opening from one side of said blade to the other,said means to immerse being adapted to position said blade with itsplane in the direction of its motion so that said straight edge extendsbeneath said top surface at an inclined angle to said top surface; and

means to feed a flexible ribbon along one side of said blade to saidopening, said means to feed being adapted to feed said flexible ribbonso that the edge of said ribbon is at an angle incident to said topsurface, said incident angle being twice said inclined angle.

3. A flexible ribbon placement means comprising:

a frame;

a reel adapted to contain a flexible ribbon, s-aid reel being supportedabove said frame;

a generally flat knife blade having two sides, said blade beingpositioned beneath said frame and adapted for immersion into andmovement through a plastic mass having a top surface with the plane ofsaid blade in the direction of said movement; and

a generally elongated eye passing laterally through the lower portion ofsaid blade, said elongated eye being at an angle of inclination to saidtop surface, said reel being positioned to feed a flexible ribbon havingtwo edges down one side of said blade with the edges of said ribbon atan angle of incidence to said top surface, said ribbon being foldedthrough said eye along a straight line and passing along the other sideof said blade with the edges of said ribbon parallel to said topsurface, said angle of inclination being about half said angle ofincidence.

4. The assembly of claim 3 wherein a vibrating means is attached to saidblade to facilitate its passage through said plastic mass.

5. The apparatus of claim 3 having reel tensioning means to maintain aconstant tension on said flexible ribbon.

-6. A machine for the edgewise placement of a flexible ribbon beneaththe surface of a plastic mass that comprises:

a track having supports at each end thereof adapted to verticallyposition said track above the top surface of said plastic mass;

a carriage slidably mounted on said track;

a reel adapted to contain a flexible ribbon, said reel being supportedby said carriage;

a generally flat blade having two sides, a forward and a rearward edge,said blade extending generally vertically beneath said carriage andattached thereto;

means for adjusting the vertical position of said blade to permit saidblade to penetrate said top surface;

a generally elongated eye laterally disposed in said blade, said eyebeing adapted to extend beneath said top surface at an angle ofinclination to said top surface when said blade is embedded in saidplastic mass;

said eye being adapted to contact and fold said ribbon along a straightline as said ribbon passes through said eye from one side of said bladeto the other;

means for feeding a flexible ribbon down one side of said blade tosaideye with the edge of said ribbon being at an angle of incidence to saidtop surface, the angle of incidence of said flexible ribbon edge to saidtop surface being about twice said angle of inclination of said eye tosaid top surface; and

means to move said carriage along said track, said blade beingpositioned so that the plane of said blade is parallel to the motion ofsaid carriage.

7. The machine of claim 6 having cutting means attached -to saidcarriage and located at the forward edge of said blade to severpreviously laid flexible ribbons positioned in said plastic mass in thepath of said blade.

References Cited by the Examiner UNITED STATES PATENTS 1,974,240 9/ 1934Heltzel 9439 r 1,982,387 11/1934 Heltzel 9445 2,025,449 12/1935 Heltzel94-39 3,194,130 7/1965 Guntert 94--45 JACOB L. NACKENOFF, PrimaryExaminer.

1. A FLEXIBLE RIBBON PLACEMENT MEANS COMPRISING: A GENERALLY FLAT BLADEHAVING TWO SIDES; MEANS TO IMMERSE SAID BLADE IN A PLASTIC MEANS HAVINGA TOP SURFACE; MEANS TO MOVE SAID IMMERSED BLADE THROUGH SAID PLASTICMASS; AN INCLINED GUIDE CARRIED BY SAID BLADE, SAID INCLINED GUIDEHAVING A STRAIGHT EDGE ADAPTED TO CONTACT AND FOLD A FLEXIBLE RIBBON ASIT PASSES FROM ONE SIDE OF SAID BLADE TO THE OTHER, SAID MEANS TOIMMERSE BEING ADAPTED TO POSITION SAID BLADE WITH THE PLANE IN THEDIRECTION OF ITS MOTION SO THAT SAID STRAIGHT EDGE EXTENDS BENEATH SAIDTOP SURFACE AT AN INCLINED ANGLE TO SAID TOP SURFACE; AND MEANS TO FEEDA FLEXIBLE RIBBON ALONG ONE SIDE OF SAID BLADE TO SAID GUIDE, SAID MEANSTO FEED BEING ADAPTED TO FEED SAID FLEXIBLE RIBBON SO THAT THE EDGE OFSAID RIBBON IS AT AN ANGLE INCIDENT TO SAID TOP SURFACE, SAID INCIDENTANGLE BEING TWICE SAID INCLINED ANGLE.